Space dyed yarns have been produced by applying different colours along the length of individual yarns. This method is expensive as the individual treatment of yarns is slow.
The Applicants have developed a process and apparatus for producing space dyed yarns by treating them in hank form. The technique superficially resembles that described in the British Patent Specification Nos. 250,899; 508,928; and 1,322,190. It is important however to realise that a dye liquor is employed and not a printing paste. The Applicants have overcome problems of production rates, definition of dye pattern and reproducibility which would arise with the prior art techniques and which make the prior art techniques unacceptable.
Objects of the invention are therefore to provide suitable apparatus for:
1. PRODUCING SPACE DYED YARNS AT HIGH PRODUCTION RATES AND AT LOW COST;
2. ACHIEVING SPACE DYE EFFECTS ON YARNS USING SIMPLE DYE LIQUORS;
3. ACHIEVING STRICTLY LOCAL APPLICATION OF DYE LIQUOR AND REDUCING THE SPREADING OF DYE LIQUOR AWAY FROM THE AREA WHERE IT WAS APPLIED;
4. OBTAINING GOOD REPRODUCIBILITY.
According to the invention there is provided apparatus for dyeing hanks which includes means for arranging dry hanks transversely on a longitudinally movable belt having transversely spaced longitudinally extending support positions; directing a narrow, continuous stream of dye liquor onto the hanks to permeate the part of the hank passing under the stream; and means for fixing the dye on the hanks.
The hanks should be dry to ensure that they absorb sufficient dye liquor and the yarns resist the passage of dye liquor only slightly. The dye liquor thus can pass through the thickness of the hank. The hank is supported by longitudinal extending transversely spaced belt parts which serve to reduce the passage of dye liquor in a transverse direction of the belt and along individual yarns. The dye liquor is applied as a continuous stream forming an uninterrupted "column" of liquor on impact with the yarn to facilitate penetration of the hanks and to reduce sideways spreading of dye liquor.
Preferably the stream is directed onto the hanks at a position between the longitudinally extending support positions of the belt. The dye liquor has a fluidity of water and is generally a dilute aqueous dyestuff solution. It contains no thickening agent. This is an important feature of the invention. This feature gives rise to the advantages of cost and speed but also makes techniques and apparatus suitable for printing or padding, inadequate in many respects in this case. Suitably the rate of delivery of dye liquor is adjustable so as to enable generally an amount of dye liquor required for permeating the appropriate part of the hank to be delivered. By appropriate adjustment waste of dye liquor can be avoided and reproducibility improved. This may also benefit pattern definition.
Advantageously a plurality of streams, at least some of which are formed by dye liquor, are directed to permeate together all of the hanks and to reduce transverse migration of dye liquor in the hanks and optionally at least some of the streams do not contain dye to provide blank areas in the hank. By wetting the whole of the hank, sideways spreading of dye liquor, due possibly to capillary action between adjacent yarns, can be reduced. Where areas are desired to be left uncoloured a stream of water not containing dye can be used.
Advantageously the permeation with dye-liquor is followed immediately by streaming so as to fix the dye and in which the belt supporting the hanks continues to carry the hanks into the steamer without any intermediate disturbance of the hanks. The dye-liquor does not adhere strongly to the yarn. By avoiding manipulation undesired displacement of dye liquor along the yarns or out of the hank can be avoided. This is important for reproducibility. For the same reason, suitably the hanks are arranged on the belt to provide a continuous layer of substantially constant thickness.
According to the invention there is also provided apparatus for dyeing which includes an endless longitudinal belt having transversely spaced longitudinally extending support positions; means for moving the belt, an array of nozzles for directing a narrow, continuous stream of dye liquor towards the belt; and means for fixing dye adjacent the array of nozzles. Suitably the nozzles are arranged to direct the streams between the longitudinally extending support positions to reduce sideways migration of dye liquor.
The longitudinally extending support positions may be formed by links -- for example of stainless steel -- pivotably connected to one another. A preferred form of belt construction is formed by transversely extending links of metal strip bent to provide a series of longitudinally extending edge portions which are hinged together. The area in contact with the hank and thereby also undesirable wetting and staining is reduced. Excess dye liquor can drain away with great facility. The belt surface does not resist the sliding of hank parts undergoing shrinkage. The belt resists deformation in a transverse direction and is capable of carrying a heavy layer of impregnated hanks. Advantageously the links are hinged together by a pivot rod extending through the longitudinally extending parts of the strips of successive links.
The nozzles may be mounted in a variety of ways. They may be mounted on one or more support bars above the belt. The nozzles can be used to eject differently composed liquors. For example sets of nozzles may be connected to a number of manifolds, one for each set, which in turn are connected to a supply of dye liquor. To facilitate pattern changes the nozzles may be mounted on clips. Suitably the height of the nozzles above the belt is adjustable and the rate of flow of dye liquor to the nozzles is adjustable. Advantageously the dye liquor is supplied to the nozzles from tanks by pumps, a by-pass fluid circuit is provided for each tank to enable pumped liquor to be returned to the tanks, and a flow control valve is provided between the pump and the nozzles. The dye liquor in the tanks can thus be stirred and flow can be adjusted simultaneously for all the nozzles supplied from a particular tank. Preferably a tray is provided under the belt below the array of nozzles for removing excess dye liquor.
Preferably the means for fixing dye is a steamer through which the belt extends and the steamer has an insulated heated roof, which is sloped; extraction flues adjacent the entry and exit to the steamer; and heating elements located between a steaming chamber of the steamer and the evacuation chambers. The steamer can thus be used with little or no condensation which could dislocate the dye liquor before the dye is fixed.